Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON):

Solution:

import collections
h,p = map(int, raw_input().split())#10 37
mat = [list(raw_input()) for l in range(h)]
q = collections.deque([((0,0), 1)])

vis = set([(0,0)])
r  = float('inf')

while(q):
	u,d = q.popleft()

	if u == (h-1, p-1):
		r = d
		break
	for v in [(u[0]+1,u[1]), (u[0]-1,u[1]), (u[0],u[1]+1),(u[0],u[1]-1)]:
		if 0 <= v[0] < len(mat) and 0 <= v[1] < len(mat[0]):
			if v not in vis and mat[v[0]][v[1]] == '.':
				vis.add(v)
				q.append((v, d+1))

cc = collections.Counter()
for l in mat:
	for e in l:
		cc[e]+=1

if r < float('inf'):
	print cc['.'] - r
else:
	print -1